The present invention is drawn to an apparatus for precisely controlling the flow of a particulate material into a bag or other container. Specifically, the present invention is a valve which can be actuated to close a conduit through which the particulate material is flowing.
In the course of filling particulate material into bags from a dispensing spout connected to a supply hopper, it is common practice to initially fill the bag in a bulk fill operation at a relatively high speed. A final charge of material is subsequently delivered into the bag to provide a total charge weight within a bag of particular volume or weight size. One such machine is of the vertical, bottom-fill auger type machine as disclosed in U.S. Pat. No. 5,109,894 issued to Harold R. McGregor and commonly assigned herewith. As disclosed in that patent, the same, relatively high speed and relatively large diameter auger utilized for bulk feed of the initial charge of material into a bag is also utilized to top off the bag with a final charge of material. Load cells provided on the fill spout provide a reading of the initial weight charge delivered into the bag; and, thereafter, a computer or central processing unit (CPU) actuates the same fill auger at a slower speed, in response to a read-out of the initial weight charge, for a predetermined time or a predetermined number of revolutions of the auger to top off the bag.
Such a total fill system suffers from several problems. First of all, an undue time delay is caused by holding the same bag on the main filling spout while a single set of load cells record the initially filled weight of the bag, after which a computer receives and processes that filled weight data and thereafter actuates the bulk auger, at a slower speed, for a calculated number of revolutions to deliver the final charge into the bag. The total fill time is further extended by the time required to lift the vertical fill auger out of the material in the bag, and to thereafter lower the bag from the spout. Secondly, it is very difficult to obtain the required, precise control of the discharge of the slight amount of particulate material, e g., one to three pounds, for accurately topping off the bag to the total, predetermined charge weight desired.
One solution to the problem is to utilize a two stage bag filling system. In such a system, a first machine dispenses an initial, bulk charge of material into the bag at a relatively high speed from a dispensing spout. The bag is then moved to a new location where a second machine adds the final, small, top-off charge of material to the bag. One example of such a system and a machine for implementing it, is given in U.S. Pat. No. 5,979,512, granted to James McGregor, et al. and commonly assigned herewith. In operation, a bag containing the initial, bulk charge of material is delivered into the top-off station where most of the weight of the substantially filled bag is registered on a first set of load cells. A second set of load cells, preferably mounted at an elevated level on a frame assembly of the top-off station, registers and weighs the final, top-off charge dispensed into the top of the partially filled bag.
While a two stage system as described above is perfectly able to fill a bag or container with an accurate and precise charge of particulate material, two separate stations are required for the bulk fill and top-off actions. It is therefore an object of the present invention to increase the accuracy and precision of a bulk filling machine by providing it with a flow control apparatus to control the flow of the particulate material into a bag or container. It is another object of this invention to provide an apparatus that will allow a user to more accurately and precisely control the flow of particulate materials through any fill tube or conduit used in a bag filling operation.
The basic objectives of this invention are realized by providing a control mechanism for controlling the flow of a particulate material through a conduit that comprises a bladder mounted within the conduit and which is inflatable between a first, deflated state and a second, inflated state. In its first, deflated state the bladder allows the particulate material to flow freely through the conduit, and in its second, inflated state the conduit is substantially blocked by the inflated bladder and no particulate material may pass.
One embodiment of the control mechanism is arranged and constructed to be mounted on a rotatable material feed auger received within the conduit. In this embodiment the bladder is mounted on the free end of the auger within the conduit. In another embodiment of the control mechanism the bladder is mounted within the conduit on a plurality of stays. In both of these embodiments it is preferred that the bladder be centrally mounted within the conduit.
In order to actuate the bladder of the control mechanism between its first and second states, the bladder of the control mechanism is connected in fluid flow relation with a source of pressurized fluid that may selectively actuate the bladder between its inflated and deflated states. Most often the bladder has a substantially circular inflated shape. But, where a rectangular conduit is used, the bladder may have a substantially rectangular shape when inflated.
The control mechanism can also be described as a membrane mounted within the conduit and constructed and arranged to allow the flow of material through the conduit when the membrane is in a first, contracted state and to substantially block the flow of material through the conduit when the membrane is in a second, extended state. An actuation mechanism operating on pneumatic or hydraulic principles is arranged to actuate the membrane between its first and second states. As described above, the membrane may be mounted to the free end of the auger received within the conduit or may be mounted within the conduit upon a plurality of stays. Again, it is preferred that the membrane be centrally mounted within the conduit. The membrane may also be substantially circular or rectangular in shape when in its second, extended state.
A method of accurately and precisely filling a container with a predetermined charge of material through a conduit provided with a control mechanism begins with the step of positioning an open end of the conduit adjacent or in an opening in the container. Next, the conduit control mechanism is opened and a continuous flow of the material is introduced into the conduit and thereby into the container. The container is then weighed to determine whether the predetermined charge of material has been placed in the container. Alternatively, whether the predetermined charge of particulate materials has been placed in the container can be assessed on the basis of the number of turns of a feed auger or on the basis of how long the particulate material has been flowing from the conduit. When the predetermined charge of particulate material has been added to the container, the continuous flow of particulate material is cut off and the control mechanism is simultaneously actuated to a closed position, thereby substantially blocking the flow of material through the conduit to ensure that excess material already in the conduit does not enter the container.
A bag filling machine which incorporates the present invention comprises a material supply hopper having an outlet and a first flow control mechanism coupled to the outlet of the hopper to control the flow of material therefrom. A conduit having an inlet and an outlet has its inlet coupled to the flow control mechanism of the supply hopper. The first flow control mechanism is typically a gate valve or the like. A material supply auger is rotatively disposed within the conduit for conveying material through the conduit in a controllable manner. A second flow control mechanism is secured to a free end of the supply auger and is arranged and constructed to control the flow of material through the conduit. This second flow control mechanism comprises a bladder or membrane secured to the free end of the auger within the conduit. The bladder is arranged and constructed to block substantially the flow of any of the particulate material from the conduit when the bladder or membrane is in its inflated state. In order to actuate the second flow control mechanism between deflated and inflated states, a supply of pressurized fluid is coupled in fluid flow relation to the bladder. The bladder of the second flow control mechanism may be circular or rectangular when it is in its inflated state.
An alternate embodiment of an apparatus for controlling the flow of material through a conduit is preferably mounted exterior to the conduit, though portions of the apparatus may be mounted interior to the conduit. This embodiment of an apparatus for controlling the flow of material through a conduit comprises a stopper that is disposed adjacent to an open end of the conduit through which material is passed. A support device is coupled to the stopper for moving the stopper between a first, open position in which material is permitted to flow through the conduit, and a second, closed position in which the stopper is in sealing contact with the open end of the conduit so as to prevent the flow of material therethrough. A reciprocating mechanism is coupled to the support device and provides motive power to the support device for moving the stopper between its first and second positions. Preferably, the stopper will comprises an elastomeric plug that seals the open end of the conduit when the stopper is in its second, closed position.
The support device that causes the stopper to move between its first and second positions comprises a plurality of rods, each having a first end coupled to the stopper and a second end coupled to a sliding collar that is received over the conduit. Rod guides received over the conduit between the collar and stopper engage the rods and ensure that each rod moves along a vertical path.
The reciprocating device may be any device that is capable of moving the stopper between its first and second positions. The reciprocating device may be mounted directly to the conduit or may be mounted to the framework of the bag filling machine independent of the conduit. One embodiment of the reciprocating device essentially comprises a reciprocating piston that is coupled to a shaft in such a manner as to cause the shaft to rotate in response to the reciprocating motion of the piston of the power cylinder. The shaft is in turn coupled to the support device by at least one linkage such that the support device moves in conjunction with the reciprocating motion of the piston of the power cylinder. A linkage that is useful in coupling the shaft of the reciprocating device to the support device is a two bar pinned linkage having a first bar with a first end that is fixedly secured to the shaft and a second end that is rotatively pinned to the first end of a second bar. The second end of the second bar is rotatively pinned to the support device so as to impart motive power thereto.
As indicated above, the reciprocating device may be coupled to the framework of a bag filling machine or directly to the conduit. Where the reciprocating device is to be coupled to the conduit, it is preferred to mount it upon a support platform that is coupled to the conduit.